Dental handpiece



' Feb. 4, 1-969 5;,HOFFME1STER 3,425,124

DENTAL HANDPIECE Filed NOV. 19. 1963 Sh eeb of 5 Feb. 4, 1969 E. HOFFMEISTER 3,425,124 7 DENTAL HANDPIECE Filed Nov. 19, 1 Sheet 2 of 5 Feb. 4, 1969 E. HOFFMEISTER 3,425,124

DENTAL HANDPIECE Filed Nov. 19. 1963 Sheet or 5 Feb. 4, 1969 'E. HOFFMEISTER 3,425,124

' DENTAL HANDPI ECE Filed Nbv. 19. 1963 Sheet 4 of 5 Feb. 4, 1969 E. HOFFMEISTER 3,425,124

DENTAL HANDPIECE Filed Nov. 19. 1963 Sheet 5 "of 5 FIG.

United States Patent 3,425,124 DENTAL HANDPIECE Erich Hoifmeister, Biberach (Riss), Germany, assignor to Kaltenbach & Voigt, Biberach (Riss), Germany Filed Nov. 19, 1963, Ser. No. 324,736 US. C]. 32-28 11 Claims Int. Cl. A61c 1/12 This invention relates to a straight or angle handpiece for dental purposes having an electrically operated fractional horsepower motor built into the handpiece.

It has been found that these fractional horsepower motors become overheated, particularly when they are in use for a relatively long time, and this may impair the working life of such motors.

In order to obviate this disadvantage, the invention provides a dental handpiece comprising a straight or angle dental handpiece having an electrically operated fractional horsepower motor, wherein said fractional horsepower motor is provided with a cooling water jacket through which cooling water can flow, and wherein conduits are provided for the discharge of water from said cooling water jacket, said conduits being so arranged that, during operation of the handpiece, cooling water can be conveyed from the cooling water jacket for the simultaneous cooling of a tool when mounted in the straight or angle handpiece.

During operation, the cooling water for cooling the tool is heated substantially to the requisite blood temperature and there is no need for the special arrangements which have hitherto been necessary, for heating the cooling water.

The fractional horsepower motor provided with the cooling water jacket can be arranged within the handle sleeve, conveniently at the front end of said sleeve, or within the head of an angle handpiece.

The cooling Water jacket for the fractional horsepower motor can be formed by a recess in the handle sleeve or head, and the interchangeable fractional horsepower motor is in this case sealed relatively to the cooling water jacket by annular sealing elements, e.g., in the form of O-rings made of rubber or synthetic plastic material.

The feed conduit for the cooling water, and also the electrical lead,'are expediently introduced into the straight or angle handpiece through a rubber or synthetic plastic material bushing arranged at the rear end of the handle sleeve. The discharge of the cooling water towards the handpiece tool is effected through appropriately shaped pipes, if necessary with interposition of flexible tubes made of synthetic plastic material.

The fractional horsepower motor with the cooling water jacket, may be built into a sleeve which comprises at its rear end a rubber or synthetic plastic material bushing through which the feed pipe for the cooling water and the electrical lead for driving the fractional horsepower motor are taken, and over the sleeve there is fitted a handle sleeve which at the front end is constructed as a handpiece nose or as a straight or angled head sleeve provided with an angle handpiece head. Handpiece noses or heads with head sleeves are provided in a manner known per se with gear elements, the gearwheel at the rear end of the handpiece nose or head sleeve meshing with a gearwheel situated on the front end of the motor shaft.

The handle sleeve in this form of embodiment is constructed at its rear end in such a manner as to be lockable to the inner sleeve, for example, by means of a bayonet joint.

The tube for discharging the cooling water from the cooling water jacket is preferably taken within the sleeve towards the rear end of the said sleeve and by means of a bend passes through slots in the sleeve and handle sleeve. Clamped to the handpiece nose or head sleeve by means of a spring clip is a small pipe which conducts the cooling water issuing therefrom towards the tool, and the said bend and said small pipe are adapted to be connected by a flexible plastic pipe.

The pipe for discharging the cooling water from the cooling water jacket can also be taken out of the handle sleeve in the forward direction through an aperture in the handle sleeve, parallel to the axis of the said sleeve, and connected by means of a short flexible plastic pipe to the small pipe clamped to the head sleeve.

In the form of embodiment hereinbefore referred to, the size or output of the fractional horsepower motor on the one hand and the volume or cross section of the cooling water jacket on the other hand, is limited. With respect to a desired temperature of 40 C. for the cooling water discharged at the front end of the handpiece, this requires that about 50 cm. /min. of cooling water issue from the handpiece and pass into the patients mouth. This relatively considerable quantity of water may be a nuisance for the patient even if he is provided with a saliva extractor.

In order to reduce the quantity of cooling water entering the patients month per minute from the front end of the handpiece, there may be arranged adjacent the handle sleeve a detachable sleeve of widened cross section and within this sleeve there is arranged a fractional horsepower motor of increased cross section and/or a cooling water jacket of increased volume.

If a fractional horsepower motor of increased cross section is provided within a sleeve of increased cross section, with the same motor power there is less heat loss. The same is the case when the volume of the cooling water jacket is increased. The reduction in the quantity of cooling water flowing through the cooling water jacket does not in any case cause a substantial variation in the temperature of the cooling water issuing from the front end of the handpiece, so that, a reduced output of water per unit of time from the front end of the handpiece, can be achieved without impairing the desired cooling effect.

According to one form of embodiment of the invention, the outer wall of the cooling water jacket is formed by the connecting sleeve of the handpiece which is widened in cross section relatively to the handle sleeve. The external temperature of the connecting sleeve can rise to, e.g., 60 C.; but it is not likely that the dentist can grip the instrument by the connecting sleeve and thus be subjected to uncomfortable heat, since the connecting sleeve is arranged outside the handle sleeve which the dentist is intended to grip, at the rear end of the said handle sleeve.

The feed conduits for the cooling water and for the electrical leads are expediently introduced into the straight or angle handpiece through the rubber or synthetic plastic material bushing arranged at the rear end of the connecting sleeve. The discharge of the cooling water towards the dental tool is effected from the connecting sleeve through appropriately constructed small pipes or conduits possibly with interposition of flexible pipes made of synthetic plastic material or rubber.

Conveniently, the connecting sleeve accommodating the fractional horsepower motor with the cooling water jacket is connected detachably such as by a screw connection, to the rear end of the handle sleeve. This form of embodiment makes it possible for varieties straight or angle handpieces for belt or cable-sheath drive to be converted in a simple manner for being driven by an electrically operated fractional horsepower motor.

As regards the discharge of cooling water towards the tool, it is proposed that the conduit used for discharging the cooling water from the fractional horsepower motor be taken out through the handle sleeve and then to the front of the handpiece.

Expediently, the fractional horsepower motor is arranged with the cooling water jacket in a special mounting sleeve which bears against the inner wall of the widenedsection sleeve. In order to guarantee as flush bearing contact as possible between the mounting sleeve and the widened sleeve, the widened sleeve may be flared conically towards the rear from the handle sleeve in the manner of a truncated cone.

In order to eliminate reliably the risk that the dentist may burn his hand if he accidentally takes up the handpiece by the widened sleeve part, the widened sleeve may be covered by heat-insulating material at its external periphery.

For a better understanding of the invention and to show how it may be carried into effect, the same will now be described, by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 is a longitudinal sectional view of an angle handpiece according to one embodiment of the invention,

FIGURE 2 is a cross-sectional view along line IIII of FIGURE 1,

FIGURE 3 is a longitudinal sectional view of a handle sleeve with a straight handpiece nose,

FIGURE 4 is a view in longitudinal section, partly in side view, of a modification,

FIGURE 5 is a longitudinal section, partly in side view, of a further embodiment of the invention,

FIGURE 6 is a detail showing, in side view, of the construction of the connection to the rear end of the handle sleeve,

FIGURE 7 is a cross-sectional view of an angle handpiece head with a fractional horsepower motor built into it,

FIGURE 7 is a cross sectional view of an angle headpiece head with a fractional horsepower motor built into it,

FIGURE 8 is a longitudinal sectional view of a further variant of an angle handpiece, and

FIGURE 9 shows another form of the type shown in FIGURE 8.

In the embodiment shown in FIGURES 1 and 2, 1 designates a sleeve which at its front end comprises an insert member 2 which is securely mounted in the sleeve. The insert member 2 comprises at its front end an inwardly projecting collar 3 and at its rear end a similarly inwardly projecting collar 4. Arranged detachably in the insert member is an electrically operated fractional horsepower motor 5, sealing elements 6, 7 preferably in the form of L-rings made of rubber or synthetic plastic material being provided which seal the fractional horsepower motor 5 relative to the insert member 2. The fractional horsepower motor is fixed within the insert member 2 by means of a threaded ring 8 whereby the motor is pressed against the rear sealing element 7 which is situated in a recess in the front face of the rear collar 4 of the insert member 2.

Screwed into the rear end of the sleeve 1 is an annular member 9 which serves as a support for a rubber bushing 10. Extending through this rubber bushing 10 is a flexible plastic pipe 11 which in axial bores accommodates a flexible plastic pipe 12 for the supply of cooling water and a further flexible plastic pipe 13 for the electrical lead 14 for driving the fractional horsepower motor 5. The electrical lead 14 extends within the interior of the sleeve 1 towards the fractional horsepower motor 5. The flexible plastic pipe 12- is connected by means of a pipe 15 passing through the insert member 2, to a chamber 16 between the front collar 3 and the rear collar 4 of the insert member 2. This chamber 16 constitutes a cooling water jacket for the fractional horsepower motor 5.

The discharge of cooling water is effected through a pipe 17 which projects into the cooling water jacket 16. This pipe 17 extends toward the rear end of the sleeve 1 and issues from the sleeve in the form of a bend 18.

Fitted on to the sleeve 1 is a handle sleeve 19 whose rear end is locked by means of a rotatable sleeve 20, which acts as a bayonet joint, to the rear end of the sleeve 1 (see also FIGURE 6). The front end of the handle sleeve 19 is constructed with an angled head sleeve 21, which in turn, has at its front end an angle handpiece head 22. A central gear element 23 is rotatably mounted by means of ball bearings 24 and 25 within the head sleeve 21. An upper gear element 26 which is mounted in ball bearings 27 and 28, is situated within the head 22. A shank 29 of a tool 30 is detachably arranged in the upper gear element 26. Detachably fixed by means of a spring clip 31 to the head sleeve 21 is a small pipe 32 whose forward bent-over end is directed towards the tool 30, while the rear end is connected by means of a flexible plastic pipe 33 to the pipe bend 18 which extends through a slot 34 at the rear end of the sleeve 1 and a further slot 35 at the rear end of the handle sleeve 19. After the handle sleeve 19 is mounted on the sleeve 1 and the two sleeves are locked by means of the bayonet joint, a gearwheel 36, at the rear end of the central gear element 23, comes into engagement with a gear-wheel 37 mounted on the front end of the motor shaft of the fractional horsepower motor.

In FIGURE 3, there is shown a handle sleeve 38 which can also be mounted on the sleeve 1 of FIGURE 1. The handle sleeve 38 is provided at the front end with a handpiece nose 39. Situated within the handpiece nose 39 is a gear element 40 which is mounted on ball bearings 41 and 42 in the handpiece nose. 'Dhis gear element carries at its rear end a gearwheel 43 which after the handle sleeve 38 has been mounted on the sleeve 1 comes into engagment with the gearwheel 37 at the front end of the shaft of the fractional horsepower motor 5.

According to FIGURE 3, a small pipe 45 whose front end extends in the direction towards the tool which is to be inserted in the handpiece nose, is mounted on the lhandpiece nose 39 by means of a spring clip 44. The rear end of the small pipe 45 is adapted to be connected by means of a flexible plastic pipe 46 to the outwardly projecting end of the bend 18.

The construction of the embodiment shown in FIG- URE 4 corresponds substantially to that of the embodiment shown in FIGURES 1 to 3. Like parts are designated with like reference numerals.

In this embodiment, the fractional horsepower motor 5 is arranged substantially in the central part of the sleeve 1 and thus of the handle sleeve 19. This requires a longer shaft 47 for the fractional horsepower motor 5, which shaft is mounted additionally at its front end by means of a ball bearing 48 in the sleeve 1. After there has been mounted on the sleeve 1, the handle sleeve 19 which is equipped at the front end as shown in FIGURE 4 with the head sleeve 21 and the angle handpiece head 22, or the handle sleeve 38 which is constructed at the front end as handpiece nose 39, the gearwheel 36 or 43 as appropriate comes into engagement with the gearwheel 37 at the front end of the motor shaft 47.

By shifting the fractional horsepower motor 5 substantially into the middle of the sleeve 1 as shown in FIGURE 4, the advantage is obtained over the constructional form shown in FIGURES 1 to 3, that the fractional horsepower motor is situated at some distance from the gear elements 36 or 43 and 48, so that the lubricant for these driving wheels cannot get into the fractional horsepower motor 5.

The form of the embodiment shown in FIGURE corresponds substantially to the form of the embodiment shown in FIGURE 1. Like parts are designated with like reference numerals.

One difference consists of the discharge of cooling water-from the cooling water jacket 16 of the fractional horsepower motor 5. In the embodiment shown in FIG- URE 5, the pipe 49 for discharging the cooling water from the cooling water jacket extends through an aperture 50 in the handle sleeve 19 forwardly, parallel to the axis of the said sleeve. The front end of the cooling water discharge pipe 49 is connected by a short flexible plastic pipe '51 to the rear end of the small pipe 32 which is connected by a spring clip 31 to the head sleeve 21.

FIGURE 7 shows the mounting of a fractional horsepower motor 52 within the head 53 of an angle headpiece. The tool shank 54 of the tool 55 is mounted in the hollow shaft of the fractional horsepower motor. The cooling water jacket 56 is formed by appropriate recesses in the head 53. In front of and behind the cooling water jacket 56 there are situated, in recesses of the head, annular sealing elements 57 and 58 which can be made as O-rings of rubber or synthetic plastic material, and which effectively seal the cooling water jacket 56. The electrical lead 59 is taken through a bore 60 to the rear end of the fractional horsepower motor 52. The cooling water feed pipe 61 extends into the cooling water jacket 56. Also extending into the jacket 56 is the small pipe 62 whose end projects from the angle handpiece head 53 and extends in the direction towards the tool 55. The rear end of the head 53 is closed by a screw cap 63 which can be unscrewed for replacement of the fractional horsepower motor 52. The screw cap 63 is also used for retaining the fractional horsepower motor 52 in the axial sense.

In the embodiment shown in FIGURES 8 and 9 there is arranged behind the handle sleeve 38, a detachable sleeve 64 of widened cross section and within this sleeve 64 there is disposed an increased-volume cooling water jacket 16. In the embodiment shown in FIGURE 9, a fractional horsepower motor of larger cross section is also mounted within the widened sleeve 64. Of course, this larger-section fractional horsepower motor may also be extended in the sense of its length.

In the embodiment shown in FIGURE '8, the outer wall of the cooling water jacket 16 is formed by the widened sleeve 64. In the embodiment shown in FIGURE 9, on the other hand, the fractional horsepower motor 5 and the cooling water jacket 16 are arranged in a special mounting sleeve 65. The mounting sleeve 65 bears on the inner wall of the widened sleeve 64. The mounting sleeve 65 can be connected to the widened sleeve 64 such as by press-fit, cementing-on or the like.

As FIGURES 8 and 9 show, the sleeve 64 of widened cross section is flared conically towards the rear from the handle sleeve 38 outwards in the manner of a truncated cone.

The conduit 75 for discharging the cooling water according to FIGURE 8 or the corresponding conduit 76 according to FIGURE 9 can, as in the case of the forms of embodiment shown in FIGURES 4 and 5 respectively, either extend along the outside of the handpiece or can be taken forwardly through the handle sleeve towards the tool 30.

As the drawings show, the widened sleeve 64 is connected releasably to the rear end of the handle sleeve 38. Releasable connection is effected by a bayonet joint with the help of a union nut 77. The connection is substantially constructed as in the case of the aforesaid forms of embodiment.

As FIGURES 8 and 9 also show, the feed conduit 66 for the cooling water and the electrical lead 67 are combined to form a common hose 68 and introduced into the dental handpiece through a rubber or synthetic plastic material bushing 69 arranged at the rear end of the widened sleeve 64. Within the connecting sleeve 64, the lead 67 and water feed conduit :66 are separated from one another. The bushing 69 is inserted in a mount 70 which is screwed to the widened sleeve 64.

The shaft 71 of the fractional horsepower motor 5 is coupled substantially at the place where it issues from the sleeve 64 through the agency of a conventional gear 72 with the driving shaft 74 which is mounted in the handle sleeve 38. In order to insure that the dentist cannot burn himself if he should happen to grasp the widened sleeve 64, the said sleeve 64 is provided as shown in FIGURE 9, with an external peripheral covering formed by a layer 78 of heat-insulating material.

What is claimed is:

1. A dental handpiece comprising a handle sleeve, a econd sleeve detachably connected to the handle sleeve and including a portion having a cross-section of greater size than that of the handle sleeve, an electrically operated fractional horsepower motor mounted within said portion of the second sleeve, a cooling water jacket through which cooling water can flow, said jacket being mounted in said second sleeve and surrounding the motor to cool the same, said jacket having a greater cross-sectional extent than that of said handle sleeve, and a conduit coupled to and providing for the discharge of water from said cooling water jacket, said conduit being so arranged that cooling water can be conveyed from the cooling water jacket toward and for the concomitant cooling of a tool mounted in the handpiece.

2. A handpiece as claimed in claim 1, wherein the cooling water jacket includes an outer wall formed by a said second sleeve of widening cross-section.

3. A handpiece as claimed in claim 2, wherein the fractional horsepower motor and the cooling water jacket are arranged in a mounting sleeve which is supported on the wall of widening cross section.

4. A handpiece as claimed in claim 1, wherein said second sleeve flares conically with increasing diameter away from the handle sleeve in the manner of .a truncated cone.

5. A handpiece as claimed in claim 1, wherein the conduit for discharging cooling water extends through the handle sleeve and forwardly so as to be directed towards a tool fitted in the handpiece.

6. A handpiece as claimed in claim 1, wherein the second sleeve includes an external peripheral covering of heat-insulating material.

7. A dental handpiece comprising a sleeve, an electrically operated fractional horsepower motor mounted in said sleeve, a cooling water jacket through which cooling water can flow, said jacket being mounted in said sleeve and surrounding the motor to cool the same, a bushing in said sleeve enclosing said jacket, a feed pipe for cooling water extending through said bushing to the jacket, an electrical lead extending through said bushing and connected to the motor to energize the same, a handle sleeve fitted over the first said sleeve and including a tool-containing portion, and conduit means connected to said jacket and extending externally of said handle sleeve for conveying cooling water from the jacket for discharge toward a tool in the tool-containing portion.

8. A handpiece as claimed in claim 7 comprising a gear on said motor for being driven thereby, and transmission means in said tool-containing portion engageable with said gear for driving a tool mounted in said tool-containing portion.

9. A handpiece as claimed in claim 7 wherein said handle sleeve is detachably mounted on the first sleeve, the handpiece further comprising a bayonet joint for Selectively locking the sleeves together.

10. A handpiece as claimed in claim 7 wherein said References Cited conduit means comprises a conduit extending Within said UNITED STATES PATENTS first sleeve and lncluding a bend extending through slots provided in said first sleeve and handle sleeve, a pipe 2,609,525 9/1952 Gemmlu 31050 connected to the tool-containing portion and a flexible 2,899,745 8/1959 Flafland 3228 plastic pipe connecting the latter pipe and said bend. 5 FOREIGN PATENTS 11. A handplece as claimed 1n claim 10 comprising a 883,684 12/1961 Great Britain.

spring clip connecting said pipe to the tool-containing ROBERT PESHOCK, Primaly Examiner. 

1. A DENTAL HANDPIECE COMPRISING A HANDLE SLEEVE, A SECOND SLEEVE DETACHABLY CONNECTED TO THE HANDLE SLEEVE AND INCLUDING A PORTIKON HAVING A CROSS-SECTION OF GREATER SIZE THAN THAT OF THE HANDLE SLEEVE, AND ELECTRICALLY OPERATED FRACTIONAL HOSREPOWER MOTOR MOUNTED WITHIN SAID PORTION OF THE SECOND SLEEVE, A COOLING WATER JACKET THROUGH WHICH COOLING WATER CAN FLOW, SAID JACKET BEING MOUNTED IN SAID SECOND SLEEVE AND SURROUNDING THE MOTOR TO COOL THE SAME, SAID JACKET HAVING A GREATER CROSS-SECTIONAL EXTENT THAN THAT OF SAID HANDLE SLEEVE, AND A CONDUIT COUPLED TO AND PROVIDING FOR THE DISCHARGE OF WATER FROM SAID COOLING WATER JACKET, SAID CONDUIT BEING SO ARRANGED THAT COOLING WATER CAN BE CONVEYED FROM THE COOLING WATER JACKET TOWARD AND FOR THE CONCOMITANT COOLING OF A TOOL MOUNTED IN THE HANDPIECE. 